Blasting explosive



Patented Mar. 26 1929.

UNITED STATES PATENT OFFICE.

LEAVIT'J. N. BENT, OF HOLLY OAK, DELAWARE, ASSIGNOR TO HERCULES POWDERCOMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

BLASTING nxr'iosrvn.

No Drawing.

My invention relates to an improvement in blasting explosives and moreparticularly to that type of explosives known as permissible explosivesand which are used more particularly in coal mines.

Explosives of the type to which my 1nvention relates have heretoforeincluded in their composition explosive ingredients, a carbonaceousingredient and a sensitizer. For example, such explosives compriseammonium nitrate, sodium nitrate, nitroglycerine and a carbonaceousmaterial such as, wood meal, sawdust, bagasse and the like.

In selecting the carbonaceous material a material of low density anddesirable absorbency has been sought in order to obtain an explosive ofmaximum low density and one in which the nitroglycerine, or other liquidexplosive, used as a sensitizer will not be unduly absorbed, especiallyin warm weather, in order that the explosive will be of desiredsensitivity without the use of an excessive amount of the sensitizer.

Heretofore in explosives of the character indicated, it has beencustomary to utilize finely divided spruce or white pine wood as thecarbonaceous ingredient and it has been suggested to use bagasse, or thewaste of sugar mills, and woods having an extremely low density, as forexample, balsa wood. Spruce and white pine wood are relatively dense andbagasse and balsa wood are relatively diflicult to obtain and areundesirably absorbent.

Now it is the object of my invention to provide a carbonaceous materialfor use in explosives which will have desirable low density andabsorbency, which will be readily produced and which may be effectivelyproduced from the woods heretofore used and from woods not heretoforeusable, such as southern yellow pine, which has not been adaptable foruse in explosives because of high density and undesirably lowabsorbency. Further, it is the object of my invention to produce amaterial of the character indicated for use in explosives, which willhave a low density enabling the produc- Application filed July 26, 1927.Serial No. 208,661.

tion of explosives giving high cartridge count per unit of weight andwhich W111 have a desirable absorbenc enabling ellicient impregnationwith sa ts, components of the explosive, where desirable, and enabling adesirable incorporation in the explosive of nitroglycerine, or otherliquid explosive, used as a sensitizer.

In the production of acarbonaceous material for use in explosives inaccordance with my invention, wood, which may be spruce, white pine,southern yellow pine, or other wood, and which has been chipped orfinely ground, is subjected to treatment, in a closed container, with anelastic fluid at high pressure and temperature and then discharged intoan area of low pressure, as atmospheric pressure. The treatment with theelastic fluidis preferably efiected through the use of steam and thetreatment continued for such time as may be necessary to efiect eualization of the pressure within and without the particles of wood,while at the same time avoiding charring or disintegration of the wood.When a very high pressure treatment is used and the temperature of steamat such pressure is injuriously high, the wood ma be given a preliminaryshort treatment with steam and then subjected to treatment with anotherfluid, for example, air, under a pressure greater than the steampressure and which may be desirably high without at the same time beingat a temperature which will injure the wood.

The wood, after treatment with an elastic fluid, as indicated, isdischarged from the chamber under the pressure therein, into an area ofrelatively low pressure, as atmospheric, which causes the pressurewithin the particles of wood to explode the particles, disrupting thefibres thereof and efi'ecting disintegration of the wood. In thedischarge of the wood from the closed chamber, the pressure therein isdesirably maintained and the discharge is preferably effectedprogressively through a narrow or re stricted opening, in passingthrough which cordance with the method disclosed in the U. S. patents toWilliam H. Mason, No. 1,586,159, dated May 25,. 1926, and No. 1,578,609,dated March 30, 1926, the fluid should have a pressure of at least 275pounds to the square inch and may be as high as from 300 to 600 poundsper square mch. Where the wood is first treated with steam at highpressure and temperature and then with, for example, air, at a higherpressure than that of the steam, the pressure of the steam may be sayabout 300 pounds per square inch and the air may be under a pressure offrom 400 to 600 pounds per square inch, or even as high as 1000 poundsper square inch. The treatment of the wood with an elastic fluid at hightemperature should be limited to a short period of time, say a fewseconds, in order that the wood shall not be charred or distintegratedby the heat, the subsequent treatment with air, if

such is utilized, may be for a longer period.

The distintegrated fibre obtained by discharge of the wood from thecontainer may be Washed and dried before use, or it may be extracted,or, if it is produced with the use of a resinous wood, it may beextracted with a solvent for rosin, as gasoline or other lighthydrocarbon solvent, for the recovery of rosin.

The distintegrated wood may be used in explosive compounds in amountfrom about 1% to about 18% and may be used in explosives of anywell-known compositionas, for example, in a composition containin thefollowing ingredients in amounts within the ranges set forth in thefollowing formula:

Per cent. Ammonium nitrate 25-85 Sodium nitrate 0-25 Nitroglycerine, orother liquid H. E..- 515 Disintegrated wood 1-18 The disintegrated woodmay be utilized with other carbonaceous materials if desired and, as hasbeen indicated, the distintegrated Wood may be impregnated with ammoniumand/or sodium nitrates and with which other salts may be included.

Having now fully described my invention, what I claim and desire toprotect by Letters Patent is 1. -An explosive composition including anexplosive ingredient and wood normally of high density, which has beendistintegrated by the release of high internal pressure.

2. An explosive composition including ammonium nitrate, a normallyliquid high explosive and wood normally of high density Which has beendisintegrated bythe release of high internal pressure.

3. An explosive composition including ammonium nitrate, sodium nitrate,nitroglycerine and wood normally of high density which has beendisintegrated by the release of high internal pressure.

4. An explosive composition including 25%80% of ammonium nitrate, 0%25%of sodium nitrate, about 10% of nitroglycerine and 1%18%'of woodnormally of high density which has been disintegrated by the release ofhigh internal pressure.

In testimony of which invention, I have hereunto set my hand, atWilmington, Del., on this 19th day of J uly, 1927.

LEAVITT N. BENT.

